The present invention is directed to a ramp generator and more particularly to a ramp generator for use in a signal processing system for a bar graph display.
In a typical bar graph display as shown in FIG. 1, two separate bar graphs #1 and #2, have 100 elements. These elements are in actuality gas tubes which may be activated to produce a glowing or illuminated bar length which is proportional to an unknown analog input signal. The display elements are activated by a three phase system indicated at 11 where in the scanning mode of, for example, 70 hertz or greater the three phases are successively activated. A particular segment or element can only be activated if the previous element has already been activated. Thus, the display will produce at a normal viewing distance a continuous but precisely controlled bar length. The display anodes are switched on and off at an appropriate clock count to determine the heighth of the bar. Such switching is determined by comparing the unknown analog signal with a reference voltage ramp.
All of the foregoing is produced and sold by the Burroughs Corporation, Electronic Component Division, P.O. Box 1226, Plainfield, New Jersey 07061.
One of the difficulties in the foregoing circuit is the ramp generator. Normally, the generator must be frequently calibrated and other efforts must be made to insure its accuracy. In the case of an integrating circuit where tolerance variations must be accommodated, it is very difficult ot economically construct a sufficient ramp generator.